The term "expatriates" refers to professionals and their families who live abroad for several months or years. Owing to potential prolonged exposure, and living conditions that may be closer to those of the local population, they are at higher risk of acquiring infectious diseases that are endemic in their new place of residence. They often have reduced access to medical services, putting them at higher risk of complications and more severe outcomes. Vaccination is probably one of the most effective means of preventing expatriates from acquiring endemic or epidemic diseases. Incapacitation or sickness in the field may cause serious disruption to project activities and impose an extra workload on the local team. It may also result in repatriation, with further extra direct and indirect costs for the organization. Predeparture advice and preparation, to promote risk reduction behavior, coupled with adequate support in the field are key ingredients to ensure effective and successful activities of collaborators. Institutions and organizations sending expatriates to developing countries have a clear responsibility, and it is in their own interests to promote the health of their employees working abroad.